Manila 20 July 2009. Scientific evidence continues to mount. The climate is changing, effects are already being felt, and human activities are the principal cause.

“Without effective action, climate change is going to be larger and more difficult to deal with than we thought,” said Dr. Chris Field, coordinating lead author of the report issued by the Nobel-winning Intergovernmental Panel on Climate Change (IPCC).

Climate change results as the Earth’s atmosphere prevents the heat generated after light hits the ground from radiating back into space. This condition is attributed to the 30% rise in carbon dioxide since pre-industrial times from the use of fossil fuels burnt by motor vehicles, power stations, and other human activities.

Data collected by IPCC shows that greenhouse gas emissions grew by an average of 3.5 % a year from 2000 to 2007. “That’s far more rapid than we expected and more than three times the 0.9 growth rate in the 1990’s,” Dr. Field said.

Carbon dioxide is just one of the so-called greenhouse gases produced. Others are almost exclusively produced by human activity such as chlorofluorocarbons (CFCs), from air conditioners and refrigerators, and nitrogen compounds. Ground level ozone, produced by burning fossil fuels, is also considered a greenhouse gas.

According to science, climate is weather averaged over the long term: decades, centuries, and millennia. It is a tremendously complex system that comprises not only the atmosphere, but also the oceans, ice, the land and its features, as well as rivers, lakes, and sub-surface water. The sun’s output, the earth’s rotation, and the chemical composition of the atmosphere and ocean all affect this system. Changes in any of these internal or external factors are responsible for the climate’s variability.

While the climate has undergone some wild shifts over the course of geological history, it has been relatively stable during the period in which modern human society has evolved. But with the increased warming that is projected from the gases that humans add atmosphere, this stability may come to a man-made end.

“Climate change means much more than higher global temperatures,” pointed out former Philippine Senator Heherson T. Alvarez, one of convenors of the Asia-Pacific Leaders Conference on Climate Change in Manila. “Global warming could result in a wide range of catastrophic consequences.”

In 2007, the IPCC predicted that sea levels will rise by up to 59 centimeters (or 23 inches) before 2100 due simply to the expansion of warmer ocean waters. With a coastline of 18,000 kilometers, the Philippines is very vulnerable to sea level rise. Since 1965, the government weather bureau reported of “an increasing trend in the sea level rise.”

But that’s not only for starters. Health-wise, there are far more harrowing consequences: devastating heat waves, poisonous plants producing more potent toxins, air quality plummeting on summer days, and disease-carrying insects swarming mountain villages. These are just some of the widespread health consequences caused by climate change.

Scientists say that as earth’s thermostat continues to climb, human health problems will only become more frequent. As Dr. Margaret Chan, Director-General of the Geneva-based World Health Organization puts it: “The warming of the planet will be gradual, but the effects of extreme weather events will be abrupt and acutely felt. Both trends can affect some of the most fundamental determinants of health: air, water, food, shelter and freedom from disease.”

The UN health agency said that human beings are already exposed to the effects of climate-sensitive diseases and these diseases today kill millions. Malnutrition, much of it caused by periodic droughts, is already responsible for an estimated 3.5 million deaths each year.

Both scarcities of water, which is essential for hygiene, and excess water due to more frequent and torrential rainfall will increase the burden of diarrheal disease, which is spread through contaminated food and water. Diarrheal disease is already the second leading infectious cause of childhood mortality and accounts for a total of approximately 1.8 million deaths each year.

Some of the health effects may lie ahead if the increase in very extreme weather events continues. Abrupt change of temperatures leading to heat waves or cold spells have become widespread, causing indirectly fatal illnesses, such as heat stress or hypothermia, as well as increasing death rates from heart and respiratory diseases.

In the United States, a heat wave killed more than 700 people in the Chicago alone in July 1995. The 2003 European heat wave — involving temperatures that were 10 degrees Centigrade above the 30-year average, with no relief at night — killed 21,000 to 35,000 people in five countries.

A massive increase in the frequency of occurrence of natural disasters such as floods, earthquakes, tsunamis, forest fires have been observed in last decades and have a direct impact in human health. In 2005, hurricane Katrina left over 1,800 Americans dead and thousands more were displaced. Earlier, in October 1999, a cyclone in Orissa, India, caused 10,000 deaths. The total number of people affected was estimated at 10-15 million.

Climate change may also accelerate the spread of disease primarily because warmer global temperatures enlarge the geographic range in which disease-carrying animals, insects and microorganisms--as well as the germs and viruses they carry--can survive. Deadly diseases often associated with hot weather, like the dengue fever and malaria, are spreading rapidly throughout Asia because increased temperatures in these areas allow disease carriers like mosquitoes to thrive.

Likewise, prolonged droughts interrupted by heavy rains, favor population explosions of both insects and rodents. Recent extreme weather events have been accompanied by new appearances of harmful algal blooms in Asia and North America, and in Latin America and Asia by outbreaks of various water-borne diseases, such as typhoid, hepatitis A, bacillary dysentery, and cholera.

Other potential health problems are far less rare. For instance, warmer temperatures lead to greater concentrations of ground-level ozone, which forms on hot, sunny days when pollution from cars and other sources mix. Smog can damage lung tissue, increasing respiratory and heart disease and death. Even modest increases in smog can cause asthma in children.

“Ozone occurs more rapidly at higher temperatures, and emissions of the pollutants that form ozone can go up,” said Dr. Patrick Kinney, associate professor of environmental health sciences at Columbia University. “Just due to climate change, we expect ozone to get a little bit worse. That should have adverse consequences for human health.”

“Without urgent action through changes in human lifestyle, the effects of this phenomenon on the global climate system could be abrupt or even irreversible, sparing no country and causing more frequent and more intense heat waves, rain storms, tropical cyclones and surges in sea level,” warned Dr. Shigeru Omi, the Asian regional WHO director.

“The Philippines is extremely vulnerable to the ravages of climate change,” the World Wide Fund for Nature reminded.